1. Field of the Invention
The present invention relates to a laser resistant ventilation device and to laser resistant tape, material and article.
2. Description of the Related Art
Laser radiation has been finding increased use in medicine due to its adjustable power, the potential precision of its use and its hemostatic property. However, inadvertent application of laser energy on non-target areas or inflammable items which are present in the vicinity of laser application can lead to serious injury of the patient. One particular concern is the use of laser radiation in the vicinity of an emplaced endotracheal tube. It has been found that when laser energy is applied to conventional endotracheal tubes, the tubes are thermally degraded and, if the ventilating gas contains a high percentage of oxygen, can result in a "blowtorch" phenomenon with potentially serious adverse consequences to the patient.
In an effort to meet this potential problem, the art has used a variety of protective devices for endotracheal tubes. For instance, the tube has been wrapped with muslin or gauze that has been saturated with saline solution. While this provides a certain level of protection of the endotracheal tube, if the laser energy resides in one location for more than a few seconds, the afforded protection will be lost and the endotracheal tube will be degraded.
Another manner of protecting the endotracheal tube is by wrapping the tube with copper or aluminum foil which is in tape form. Although the metallic foil generally protects the endotracheal tube, the laser energy can reflect off the surface of the foil and cause injury to non-target areas of the patient or to operating room personnel. Additionally, when the endotracheal tube is flexed, the foil can kink and impair ventilation of the patient, particularly if a small diameter tube is used, or can separate from localized areas of the tube, leaving gaps in the protection and exposing relatively sharp edges which can injure the patient upon removal. The metallic foil can also degrade the inflatable cuff and therefore is spaced from the cuff which detracts from the area of laser protection afforded the tube.
A commercially available kit designed to provide laser protection to conventional endotracheal tubes involves a micro-corrugated silver foil that is wrapped around the tube and is in turn enveloped in a hydrophilic sponge comprised of the reaction product of polyvinyl alcohol and formaldehyde. The sponge is described in U.S. Pat. No. 4,098,728.
Another manner of protecting conventional endotracheal tubes is described in U.S. Pat. No. 5,103,816. As set forth therein, the tube is spirally wrapped with a composite of an adhesive layer, foil, a fire retardant fabric and a hydrogel.
Other attempts at laser resistant endotracheal tubes involve the construction of the tube itself. For instance, the so-called Baxter-Norton tube is constructed of an interlocked, flexible, stainless steel, spiral with the distal tip and the ventilator connector brazed thereon. The tube is not airtight and is not provided with an inflatable cuff.
U.S. Pat. No. 4,834,087 and its division, U.S. Pat. No. 5,040,531, describe an endotracheal tube constructed of an airtight flexible tube having a matte outer surface to reduce reflection. However, the matte surface tends to absorb laser energy causing a significant increase in the temperature of the metal which can cause thermal damage to the surrounding tissue.
Other types of endotracheal tubes are constructed of an aluminum and silicone spiral with a silicone covering or a silicone tube covered with a protective aluminum-filled silicone layer. The silicone-containing materials generally do not provide a sufficient level of laser resistance. Furthermore, if they are thermally degraded by laser energy, an ash-like material remains which can be difficult to completely remove from the patient.
A further type of laser resistant endotracheal tube includes a piece of flat aluminum foil that is spirally wrapped around a cuffed tube. The aluminum foil is not adhesive backed, but is maintained in place by the pressure of the spiral wrapping and secured near the proximal end of the tube with tape. The aluminum foil layer is covered with a Teflon overwrap. The absence of adhesive on the foil makes such an endotracheal tube relatively difficult to manufacture and has the potential of unraveling. Additionally, if the Teflon overwrap is impacted with laser energy, it can cause a medical condition known as "plume polymer fever". Furthermore, if the laser energy burns through the Teflon overwrap and impacts the aluminum foil layer, it can reflect and cause injury to the patient or surgeon.
A discussion of various types of endotracheal tubes used in laser surgery and their performance is in "Health Devices", Vol. 19, No. 4, pages 109-139 (April 1990).
An ancillary problem with respect to endotracheal tubes designed to be used in laser surgery is placing the tube in the correct position within the patient. Conventional endotracheal tubes have marks to indicate distance from the distal end. However, dark marks tend to absorb laser energy and are thus omitted from certain tubes designed for use with laser surgery. Additionally, the material of construction of some laser resistant tubes is difficult to mark and marking is likewise omitted. This problem and a technique for measuring the depth of unmarked endotracheal tubes is described in a Letter to the Editor by Dr. Wayne S. Matthews, Jr. in Anesth. Analg., Vol. 70, page 340 (1990).
Despite the numerous developments that have been made in the art, significant drawbacks remain and the art has continued its search for an effective laser resistant endotracheal tube and material. Improved techniques for protecting articles and individuals from laser energy are also being sought in the art.